Embryology: Inconvenient Facts

In the ongoing debate about cloning human embryos for research, and about destroying them in order to harvest their stem cells, it is important to keep some basic facts in mind. Our moral analysis must be built upon fundamental scientific truths. If we obscure the facts, then we will not think clearly or act responsibly about these issues.

Every human being begins as a single-cell zygote, grows through the embryonic stage, then the fetal stage, is born and develops through infancy, through childhood, and through adulthood, until death. Each human being is genetically the same human being at every stage, despite changes in his or her appearance.

Embryologists are united on this point. Consider the following statements from standard textbooks: "Human development begins at fertilization.... This highly specialized, totipotent cell marked the beginning of each of us as a unique individual" (Keith L. Moore and T.V.N. Persaud); "Almost all higher animals start their lives from a single cell, the fertilized ovum (zygote).... The time of fertilization represents the starting point in the life history, or ontogeny, of the individual" (Bruce M. Carlson); "Although life is a continuous process, fertilization is a critical landmark because, under ordinary circumstances, a new, genetically distinct human organism is thereby formed.... The embryo now exists as a genetic unity" (Ronan O'Rahilly and Faiola Muller).Normally, the embryo comes into being through sexual conception, in which the female egg cell is fertilized by a male sperm cell. In sexual reproduction the new individual gets half of its chromosomes from the nucleus of the sperm cell and half from the nucleus of the egg cell. The new organism thus produced is genetically distinct from all other human beings and has embarked upon its own distinctive development.

In addition to this normal process, we have developed laboratory techniques with which to manipulate the procreation of new human organisms. One of these techniques stages the encounter of sperm with egg in a laboratory dish rather than in a woman's body. This is in vitro fertilization (IVF). Another technique is an asexual one in which no sperm is involved. Instead, an egg has its nucleus removed and replaced by a nucleus from another type of cell-a body cell. The egg is then stimulated by an electrical charge, creating a living human zygote. This is cloning, a process in which the body cell that donated the replacement nucleus supplies the chromosomes of the new human organism.

Whether the new organism is produced by fertilization or by cloning, each new human organism is a distinct entity. Twins are genetic duplicates of each other, but no one would deny that each is a distinct human individual. Similarly, a clone would be a genetic duplicate of another human being, but there is no denying that it would also be a separate individual.

From its first moment, supplied with its complete set of chromosomes, each new zygote directs its own integral functioning and development. It proceeds, unless death intervenes, through every stage of human development until one day it reaches the adult stage. It will grow and it will develop and it will change its appearance, but it will never undergo a change in its basic nature. It will never grow up to be a cow or a fish. It is a human being from the first moment of its existence. As Paul Ramsey has noted, "The embryo's subsequent development may be described as a process of becoming what he already is from the moment of conception."

These are the facts, which we can either affirm or deny. Unfortunately, the denial of inconvenient facts has become quite common during the past several decades. Consider, for example, an editorial published in the September 1970 issue of California Medicine, which was then the journal of the California Medical Association. The editorial invited the Association's members to play a new game called "semantic gymnastics." The first rule of the game was the "avoidance of the scientific fact, which everyone really knows, that human life begins at conception and is continuous whether intra- or extra-uterine until death." The goal was to replace "the traditional Western ethic" respecting "the intrinsic worth and equal value of every human life regardless of its state or condition" with "a new ethic for medicine and society" in order "to separate the idea of abortion from the idea of killing."

In subsequent years, the dehumanization of the unborn was taken a step further when the concept of the "pre-embryo" was advanced. The term referred to the embryo before its implantation in the womb. Certainly the embryo at this point is "pre-implantation," and certainly implantation is a highly significant event. If the embryo does not implant, it will die; if it implants, it will receive nutrition and a suitable environment in which to live, grow, and develop. (Every human being at every stage of life similarly requires nutrition and a suitable environment.) But the critical question is: Does implantation effect a change in the nature of the thing that implants? It is clear from basic facts of embryology that it does not. In the 2001 edition of his leading textbook on embryology, Ronan O'Rahilly writes, "The term ‘pre-embryo' is not used here [because] ... it may convey the erroneous idea that a new human organism is formed only at some considerable time after fertilization. [The term] was introduced in 1986 largely for public policy reasons."

For what public policy reasons was the term "pre-embryo" invented? Princeton biology professor Lee Silver, a noted advocate of all the new biotechnologies, supplies the answer in his Remaking Eden (1997):I'll let you in on a secret. The term pre-embryo has been embraced wholeheartedly by IVF practitioners for reasons that are political, not scientific. The new term is used to provide the illusion that there is something profoundly different between a six-day-old embryo and a sixteen-day-old embryo. The term is useful in the political arena-where decisions are made about whether to allow early embryo experimentation-as well as in the confines of a doctor's office where it can be used to allay moral concerns that might be expressed by IVF patients.

As Gilbert Meilaender has noted, the "pre-embryo" is merely the unimplanted embryo. In other words, it is already an embryo, and all embryos are, at first, unimplanted. An embryo subsequently implants unless something (or someone) interferes or the embryo is defective. Its life is continuous from its first moment (whether through fertilization or through cloning) until death. The term "pre-embryo" was developed and used largely, if not exclusively, to mislead: to hide scientific facts about the beginnings and unity of human life; to bolster support for a new reproductive technology; and to obtain funding for experiments on human embryos. It has led to a confused jurisprudence that treats the embryo, in certain contexts, more like property than like a human being.

Though the term "pre-embryo" has been rejected in science, the motive for its creation-to dehumanize the early embryo in order to justify its destruction-lives on. It is part of the debate over human cloning and human embryonic stem-cell research.

In the cloning debate, the attempt to deny what "everyone really knows" by finding a more accommodating language has been so convoluted that it would be amusing if lives were not at stake. First, proponents of cloning tried to deny that cloning creates a human embryo. Since, they argued, the new entity does not result from sexual reproduction, it could not be an "embryo." For reasons I have indicated (the nature of the product of cloning as a living, genetically complete, unified, self-integrating human organism in the first stage of development) few were taken in by that ploy. Even prominent advocates of embryonic stem cell research, such as John Gearhart of Johns Hopkins University, have acknowledged that the "thing" created by cloning is an embryo.Some have asserted that the location of the thing in a Petri dish or in an IVF clinic (i.e., outside a woman's womb) means it is not an embryo. They assert that since it will never be implanted in a womb, it can never be a human being. On the Frequently Asked Questions page of the website of the Federation of American Societies for Experimental Biology we are told that "the cells resulting from nuclear transplantation are grown in a culture dish in the presence of special nutrients for only a few days, when they will comprise a cluster of about 120 cells that can be used to derive stem cells. Therefore, because the cells are never transferred to a uterus they cannot develop into a human being on their own."

The question-begging nature of this assertion should be evident: if the cells are "never transferred to a uterus," it is because the people in the lab choose not to transfer them. It is disingenuous for those who would deprive the embryo of the chance to be born to claim that their action changes the nature and status of the thing considered. This is like the Nazis claiming that concentration camp inmates are not human beings because the Nazis intend to destroy them during lethal experiments. The argument is a variation on the theme of "potentiality"-since the "cluster of cells" lacks the potential to be born, it is not a human being. But the fact is that every human being, including every embryo, is full of inherent potential by virtue of being human. That potential may never be realized or it may be impeded in particular cases. But that potential-to live, to grow, and to develop-is part of what it means to be a living human being.

The advocates of cloning have also posited a distinction between "reproductive cloning" and "therapeutic cloning." Reproductive cloning, we are told, would see the clonal zygote transferred to a uterus and would, all other things being equal, result in the eventual birth of a human being. (This is a scenario that many people fear.) Therapeutic cloning, we are assured, would never approach anything like reproduction: the clonal zygote is simply kept in the lab, an innocuous cluster of cells to be put to good scientific use. But this distinction is groundless. Once a living human zygote has been created, "reproduction" of a member of the human species has occurred, regardless of the purpose (birth or experiment) for which the clone was created. Thus, all human cloning is reproductive cloning.

Nor can the label "therapeutic" be properly applied to the cloning of a human being for the purpose of harvesting "its" useful parts and disposing of the remainder. For a procedure to be "therapeutic," it must be so for the subject of the procedure. (To drain me of my blood in order to stock a blood bank may eventuate in some therapeutic results for someone, but it is not therapeutic for me.) Medical ethics have always insisted that there be greater protection for the subject when the subject is not himself benefited by the procedure. Yet "therapeutic cloning" kills the subject (the embryo) every time (in order to get stem cells). The fact that the distinction between therapeutic and nontherapeutic procedures is so well established, with greater protection accorded subjects in nontherapeutic experiments, makes the decision of cloning proponents to use the term "therapeutic" even more troubling.

After opinion polls revealed that Americans did not like any kind of "cloning," whatever the adjectival modifier, cloning proponents took a bold gamble-they simply decided to re-name the procedure. Instead of "cloning," it would now be called "somatic cell nuclear transfer" or "nuclear transplantation to produce stem cells." But both phrases are simply definitions of cloning. Cloning is a laboratory procedure in which the nucleus from a somatic (body) cell is transferred or transplanted into an egg cell from which the original nucleus has been removed. The attempt to use five long words instead of one short one and to pretend that the five words denote something different is linguistic mischief, not science. Worse, with the phrase "nuclear transplantation to produce stem cells," cloning advocates seek to obscure a crucial fact: the procedure does not "produce stem cells"; it produces an embryo which is later killed so that its stem cells can be removed. Whatever the purpose of any act of embryo-creation may be, whether eventual birth or eventual disaggregation, it is a human embryo and thus a human being that is being produced and killed.

Human stem cells have indeed proven to have great value in the invention of new medical treatments, though it is significant that the only treatments developed to date have involved stem cells acquired nondestructively from nonembryonic sources, including adult donors. Therapies involving the use of adult stem cells are already numerous, whereas therapies derived from embryonic stem cells are still only theoretical (see, for example, Maureen L. Condic's "Stems Cells and False Hopes," FT August/September 2002). Wesley J. Smith has called the media coverage of advances in adult-stem-cell regenerative therapies "grudging," and notes that the favored theme in much media coverage is that embryos hold the key to the future.

Nonetheless, the public is becoming aware that stem cells can be obtained, nondestructively, from adults. And we are also becoming aware that the harvesting of stem cells from embryos cannot be accomplished without causing those embryos to cease to exist as organisms-that is, without killing them. My hope is that we come to understand clearly that it is a matter of scientific fact, and not of opinion, that the embryonic organisms we are being urged to exploit and discard are, like us, human beings.

William L. Saunders is Senior Fellow and Director of the Center for Human Life and Bioethics in Washington D.C. Material in this essay is adapted from a chapter in Human Dignity in the Biotech Century (InterVarsity).

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